This invention relates to an oral preparation for use in the prevention of dental caries. More particularly, this invention relates to a stable, low-pH emulsion for oral administration as a dental caries prophylactic.
It has been found that aluminum salts can be used in a flavored emulsion with selected nonionic surfactants to produce a cariostatically active low-PH composition that is both stable and palatable to humans. The oral composition may be used in the preparation of a wide variety of products, including mouthwashes, chewing gums, prophylaxis pastes, dentifrices, dental rinses, and lozenges.
Anticariogenic preparations are well known in the art. Topical formulations containing fluoride, stannous fluoride, or sodium fluoride, for example, are known to provide partial protection against dental caries. Although effective dental caries protection has been obtained through the use of such fluoride-containing compounds, occasional side effects have been experienced with certain of the known fluoride-containing anticariogenic agents, particularly certain tin-containing salts. A brownish pigmentation has been noted after anticariogenic agents containing the stannous ion have been applied to the teeth. Although the pigmentation is not necessarily undesirable from a physiological standpoint, for aesthetic reasons, it would be desirable to provide an effective anticariogenic agent that does not discolor enamel.
The utility of fluoride materials has also been limited by the extent of their solubility and stability in aqueous media. For example, sodium fluoride is only soluble to the extent of about 4% in water. Furthermore, because of toxicity concerns, current regulations imposed by the U.S. Food and Drug Administration limit the amount of fluoride that can be provided in products sold for over-the-counter use.
For the foregoing and other reasons, dental researchers have continued their efforts to develop new anticariogenic agents which not only demonstrate a high level of anticariogenic effectiveness but are non-toxic, stable, and widely available. It has been suggested that aluminum salts may have a beneficial effect in reducing dental caries or in facilitating the uptake of fluoride by the dental enamel. See, e.g., Manly, et al., J. Dent. Res. 28: 160 (1948); Regolati, et al., Helv Odont. Acta. 13: 59 (1969); and Kelada, "Electrochemical Characteristics of Free and Complexed Fluorides in drinking Water and the Effects of Aluminum and Iron on Fluoride Incorporation Into Tooth Enamel," Univ. Michigan Thesis (1972).
In vitro studies have shown that pretreatment of enamel with aluminum solutions resulted in increased fluoride uptake when followed by treatment with a fluoride solution; however, treatment with combinations of aluminum and fluoride did not afford any added benefit over that of fluoride alone. McCann, Arch. Oral Biol 14:521 (1969); and Gerhardt, et al., J. Dent Res 51:870 (1972). The foregoing techniques dealt primarily with the use of aluminum in combination with fluorides and did not focus on the effect of aluminum in the absence of fluoride.
Nor has the use of aluminum salts in dentifrices demonstrated a desirable result, primarily because there has been but recent recognition that conventional dentifrice abrasives are incompatible with sources of biologically available aluminum (U.S. Pat. No. 4,108,979). While French Patent No. 3610M describes a specific combination of aluminum lactate, aluminum fluoride, and calcium pyrophosphate, the abrasive interferes with aluminum ion activity by forming insoluble aluminum phosphate. Similarly, U.S. Pat. No. 3,095,356 uses aluminum salts such as aluminum fluoride to coact with insoluble sodium metaphosphate abrasives to reduce the solubility of such abrasives and to increase fluoride uptake, but without independent therapeutic advantage being taken of the aluminum.
Canadian Pat. No. 829,272 describes acidic dentifrices comprising a combination of surface active substances and albumen-coagulating substances such as certain carboxylic acid salts of aluminum and other metals. However, this patent fails to teach that the satisfactory use of aluminum ions in dentifrices is dependent upon the use of aluminum compatible constituents, that is, constituents which when present in solution with aluminum ions, do not complex or react with them to render said ions unreactive with the surface of teeth.
U.S. Pat. No. 4,108,981 describes an alkaline mouthwash composition (pH 7-9) comprising aluminum salts and carboxylic acid. However, that patent teaches that the carboxylic acid is required to stabilize the aluminum in the mouthwash preparation. Similarly, U.S. Pat. No. 4,153,732 teaches that ascorbic and adipic acids can be used to stabilize an aluminum-containing comestible. It further teaches that, in fact, many carboxylic acids interfere with aluminum ions. (Column 5; lines 7-9). There is nothing to suggest the use of aluminum ions without a stabilizing acid, merely that certain carboxylic acids are more compatible with aluminum.
In sum, the prior art has not heretofore suggested a stable anticariogenic preparation of aluminum ions at low pH without the presence of carboxylic acids and/or fluoride. One of the main problems associated with the formulation of such aluminum ion preparations is that aluminum is naturally very astringent, tart-tasting, and produces a profound drying sensation in the oral cavity. Another problem is that aluminum is very reactive and can easily be inactivated by many conventional cosmetic ingredients.
An object of the present invention therefore is to provide a novel, low-pH composition for inhibiting dental caries employing aluminum in a compatible emulsion system.
A further object is to provide cariostatically effective aluminum-containing oral preparations which are both stable and palatable.
A still further object is to provide new anticariogenic emulsions useful for preparation of mouthwashes, dentifrices, chewing gums, lozenges, and prophylaxis pastes.